aarch64.risu: add store exclusive insns for 8/16bit stores

add STLXRB, STLRB,
STXRH, STLXRH, STLRH.

Signed-off-by: Claudio Fontana <claudio.fontana@linaro.org>
aarch64.risu: add load exclusive insns for 8/16bit data

add LDXRB, LDAXRB, LDARB, LDXRH, LDAXRH, LDARH.

Signed-off-by: Claudio Fontana <claudio.fontana@linaro.org>
aarch64.risu: add load/store excl insns for 32/64bit data

add STXR, STLXR, STLR, LDXR, LDAXR, LDAR for 32bit and 64bit.

Signed-off-by: Claudio Fontana <claudio.fontana@linaro.org>
Merge branch 'master' of https://github.com/hw-claudio/risu-aarch64

Conflicts:
	aarch64.risu